The present invention relates to an input device that is adapted to computers, electronic typewriters and word processors.
A variety of types of keyboard switches have heretofore been proposed using organic piezoelectric materials. For example, a document No. 114 in the "1977 Joint Convention Record of Four Institutes of Electrical Engineers, Japan" discloses devices to constitute input devices such as a keyboard and a tablet for input of picture by using a polyvinylidene fluoride (PVDF) or a PZT/polymer 0-3 composite composed of a polymer blended with a powder of lead zirconate titanate (PZT) or the like. However, since the PVDF or the PZT/polymer 0-3 composite has a homogeneous composition, use of a material that is wholly polarized gives rise to the occurrence of crosstalk relative to the neighboring keys. Therefore, a considerably cumbersome step is required to constitute a keyboard by effecting local polarization to be suitable for a printed circuit in the keyboard. As for a tablet for input of picture, furthermore, a method has been developed to detect the position of a vibrating pen relying upon electrodes at four places without, however, satisfactory results in regard to resolution and quick response.
A piezoelectric material/polymer 1-3 composite, on the other hand, is used as an ultrasonic probe of a diagnostic ultrasound equipment.
The method of producing the piezoelectric material/polymer 1-3 composite of this type has been disclosed in a journal "Sensor Technology", Vol. 2, No. 7, p. 84, FIG. 6, June, 1982 (Japan).
The method of producing the piezoelectric material/polymer 1-3 composite of this kind has also been proposed in U.S. Ser. No. 661,928 that was filed previously by the inventors of the present invention.